1. Field of the Invention
The subject invention relates to a device for mechanically measuring the difference in height between a reference plane and a material buildup.
2. Discussion
Currently, there are two well known devices for measuring the height difference between a reference plane and a material buildup on the reference plane such as solder bumps on a circuit board. The first device comprises a simple cantilever probe moveable on a fixed arm with a dial indicator to indicate a change in height. Both the tool and the circuit board are placed on a granite leveling slab. The circuit board is first leveled with that of the granite slab. The probe is lowered to contact the material buildup to indicate the height difference between the material buildup and the reference plane surface of the circuit board. The tool is then moved to change the probe's position on the circuit board. The probe indicate height differences by observing the changes in the dial readings.
A second device for measuring the height difference comprises a complex computer controlled machine, such as the Zeiss, which is programmed for a series of movement, probing and recording steps. In this device, the circuit board must also be leveled with the subsurface of the machine. An arm is lowered to contact the material buildup to provide an electronic readout as to the height difference between the material buildup and the reference plane surface of the circuit board.
One of the problems with the above devices is that the circuit board must be leveled with respect to the tool being used. This requires a large amount of time for proper set-up. Further, the second device requires programming which also takes a large amount of time. Further, both devices are very costly. Finally, neither of the above two devices are easily portable.